An information processing apparatus performs monitoring based on a polling system, for example, to control processing among a plurality of apparatuses or among a plurality of processes. According to the polling system, the information processing apparatus periodically sends an inquiry to each monitoring target corresponding to a process or an apparatus, and executes a predetermined processing (hereafter called response processing) in accordance with the inquiry result.
If there are a plurality of monitoring targets based on polling, the information processing cyclically monitors the plurality of monitoring targets on a regular basis. Therefore if there is a plurality of monitoring targets, each of the plurality of monitoring targets has an equal number of times of monitoring based on polling.
In some cases, the monitoring target may change immediately after monitoring based on polling. In this case, the information processing apparatus detects the change that occurred to this monitoring target in the next cycle of monitoring after monitoring the rest of the monitoring targets. This means that when there are many monitoring targets, the time from the occurring of a change in the monitoring target to the detection of this change becomes long, and a response time to be taken unto execution of response processing becomes long.
Therefore it was proposed that a priority is assigned to each monitoring target, so that the monitoring frequency of a monitoring target having a high priority is increased.
The technique to control processing based on priority after a message arrived is disclosed in, for example, Japanese Laid-open Patent. Publication No. S63-158655 and Japanese Laid-open Patent Publication No. 2006-323752.